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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"



(phytosterol or cholesterol) of the original oils and, as a rule, traces of the
catalyst (mostly nickel) are found.

The analysis of these products includes :

1 . Characters and Origin.— Of the characters of hardened oils, those
of special importance, besides the objective ones, are the melting 'point,
solidifying point of the fatty acids (titer) and the acid, saponification and
iodine numbers.

To ascertain the origin of a hardened oil, the unsaponifiable substances
(sterols) must be extracted and identified (see Hog's Fat) : hardened animal
oils contain cholesterol and the vegetable ones, phytosterol.

The Tortelli and Jaffe reaction (see p. 430) indicates if a hardened oil
is prepared from a marine animal oil.

2. Test for Traces of Catalyst (Nickel}.— This may be made on the
ash of the product or, according to Fortini, in the following way :

5 to 10 grams of the fat are heated for half an hour on the water-
bath with as much cone, hydrochloric acid, with frequent, vigorous shaking ;
the acid is then filtered through a moist filter into a dish, evaporated to
dryness, and the residue moistened with a few drops of i% alcoholic dimethy-
glyoxime solution : in presence of nickel a red coloration is obtained, this
being rendered more evident when the solution is made slightly alkaline
with a drop of dilute ammonia.

If the extract of the acid is highly coloured it is well to redissolve it in
a little water and decolorise with animal charcoal.


This is obtained by treating castor oil with sulphuric acid, eliminating
the excess of acid by washing with water and sodium sulphate solution and
then neutralising more or less completely with ammonia or soda. It con-
sists, therefore, essentially of ammonium or sodium sulphoricinate. It is
a clear, yellow liquid with the odour of castor oil. It dissolves in a small
quantity of water but further addition of water (10 vols. per i vol. of the
oil) yields a perfect, white emulsion which persists for some hours and is
•faintly acid to litmus paper. Sulphoricinates neutralised with ammonia
or soda dissolve, however, in water in all proportions, but faint acidification
of the solution with a few drops of acetic acid results in emulsification. If
an excess of acid or sodium chloride is added, either to the emulsion or
to the solution of a sulphoricinate, an oily layer separates.

Sulphoricinates are also completely dissolved by ammonia, the solution
not being rendered turbid by dilution with water. Alcohol, too, completely
dissolves them.

Ammonium sulphoricinate gives ammonia when heated with sodium
hydroxide, while sodium sulphoricinate is incinerated and the ash examined
for soda.

Genuine Turkey-red oil is sometimes replaced by analogous preparations
with bases of sulphonated olive, arachis, cottonseed or resin oil or oleic
acid and is often adulterated with mineral oil.

It is also to be borne in mind that certain emulsive lubricating oils,   .115       0-926—0-970 j      81—83     \     80— 81